I agree that we need to be authentic to our true selves, and I have seen the harm that comes from not being yourself.

However faking for entertainment (ie playing games etc) is not the same as being inauthentic. An individual's interests are part of that authentic individual. For myself, if I was to hide all of my interests and not engage in them, I would be a less authentic version of myself. This is true for anyone who has an interest in any entertainment that is fake: whether it is reading a fictional book, roleplaying as a character while playing a pencil and paper RPG, watching a good TV show, playing a video game including VR or anything else. A person with those interests hiding those interests from other people and maybe even trying to stop themselves from engaging in their interest is less authentic to their true self than someone who embraces their interests and engages with them.

Authenticity is more about whether you are truly being yourself or not, in the big picture. Yes, technically you are not "being yourself" when you pretend to be a half-orc barbarian in Dungeons and Dragons (this also shows that this isn't anything to do with modern times since D&D has been since the 70s) but if you have a legitimate interest in it, and you play Dungeons and Dragons and are open about the fact you have an interest in it, you are being authentic. If you pretend to like it but you don't, then you're not being authentic. Role playing doesn't change authenticity, nor does playing video games, including VR games or watching TV shows. I mention D&D because there is a lot of overlap between those sorts of pencil and paper RPGs and video games but also because if anything made you not authentic due to pretending being involved, role playing games like D&D would be much more likely to do that than video games would (maybe some RPG video games may be comparable but I can't say I've seen one that still involves as much real role playing as D&D etc - most of it is "do quests", "do dungeons" etc which is fun but not as role play heavy as a pencil and paper one).

Authenticity is about being real and not fake but that doesn't apply to role playing a character in a game or watching something that is fictional (or in the case of reality TV, mostly fictional). The authenticity there is that you aren't pretending to like that game or show etc, not whether you are being yourself when in character or not. Engaging with fiction and even roleplaying is not the same as being fake / unauthentic. Interests are part of who you are authentically are.

Being yourself is the whole point of authenticity so the stuff you've mentioned as good things we have done for all of eternity will only be authentic for a person if that's how they truly feel / what they truly are interested / who they truly are. Gamers, vegetarians, reality TV show watchers, people not in a relationship or in a casual relationship, people who are in a relationship but have no desire to have kids and raise a family and many other groups can all be authentic because this stuff has no bearing on authenticity unless their reasoning for those particular aspects of themselves are inauthentic. Otherwise they are just aspects of the person or their life situation. Genuine fulfillment is also subjective too.

People also don't need to fight for purpose. We aren't born with a purpose that we have to find. We could discover talents or interests we have and that becomes our purpose, which fits if you agree with us having no inbuilt purpose and you were arguing for fighting to create a purpose for ourselves, but even then why would anyone want their life to boil down to one purpose? I wouldn't want a purpose. I'd want things that I do well, that make me happy and maybe improve the world, but I don't want a purpose funneling everything down one track towards that purpose. I'd much prefer to not have a purpose and to do multiple things in my life rather than be limited by my understanding of "this is my purpose". Searching for your purpose (which doesn't exist unless you create it yourself as we aren't born with a purpose) is just a good recipe to get depressed at the times that it doesn't work out for you. It's also limiting if you do work it out.

Certainly we need to be willing to be authentic. I definitely need to be authentic for my own health. The mask I didn't even know I was wearing fell off during a period of burnout, and while it is useful to know how to mask and pretend to be neurotypical, I don't want to put that mask on again very often and certainly not for a long period. My interests though, including things you say are not authentic, are intrinsically part of me, so no authentic version of me doesn't have and express those interests. I am far from the only one either.

It's also worth noting that upvotes on here as a fake a validation as instagram likes are.